This invention relates generally to the diagnosis of Alzheimer's Disease in humans and, more specifically, to a novel polypeptide and antibodies and nucleotide probes corresponding thereto for use in diagnostic tests.
Alzheimer's Disease is a degenerative brain disorder characterized clinically by loss of memory, confusion, gradual physical deterioration and ultimately death. The etiology of the disease is virtually unknown but has been variously attributed to viruses, toxins, concentrations of heavy metals, as well as genetic defects. It is now estimated to afflict some two million Americans, most of them elderly. The disease is at present incurable and, amongst diseases, constitutes the fourth leading cause of death in this country.
The brains of individuals with Alzheimer's Disease exhibit characteristic lesions termed neurofibrillary tangles and neuritic plaques. These result from deposits of amyloid protein within or between the neurons. Recently, it has developed that similar deposits also line the walls of the cerebral blood vessels.
Until quite recently, Alzheimer's Disease was thought to account for relatively few of the cases generally classified as senile dementia. Other factors which can lead to such a condition include repetitious small strokes, thyroid disorders, alcoholism and deficiencies of certain vitamins, many of which are potentially treatable. Until this time, there has been no useful diagnostic test for Alzheimer's Disease. A definitive diagnosis is possible only postmortem or during life through a brain biopsy to reveal the presence of the characteristic plaques, tangles and cerebrovascular deposits which characterize the disorder. Such an invasive surgical procedure is inherently dangerous and is therefore rarely utilized. As a result, the clinical misdiagnosis of Alzheimer's Disease is estimated to be approximately 20%-30%.
Therefore, there exists a need for a definitive diagnostic test which can be performed on individuals suspected of having or being at risk for Alzheimer's Disease. Desirably, such a method should be relatively simple, sensitive, accurate and painless for the patient. Additionally, it should be highly specific in distinguishing Alzheimer's Disease from other disorders. It should be non-invasive so as not to require the painful and often hazardous removal of brain tissue samples. Furthermore, it is desirable that it be capable of being reduced to a standardized format, preferably easily and quickly performed. Additionally, because of the immense numbers of individuals potentially afflicted with the disease, it is desirable that such a test be relatively inexpensive to administer. The present invention satisfies such needs and provides further advantages.